The present invention is directed to an improved re-entry gate arrangement for a strapping machine. More particularly, the present invention is directed to a re-entry gate assembly for a strapping machine in which a pair of linked gates both open upon the urging open of either gate.
Strapping machines are used for securing straps around loads. One type of known strapper includes a strapping head and drive mechanism mounted within a frame. Strapping material is fed, for a supply (e.g., a dispenser) into the chute. A typical drive mechanism includes feed wheels that “push” the material through the chute via the strapping head. The leading end of the strapping material traverses the chute and re-enters the strapping head at the end of the chute.
The strap is then rewound and tensioned around the load, the overlying strap courses welded together and the trailing end of the strapping material severed or cut from the supply. During the rewinding and tensioning step, the strap is “pulled” from the chute. During the “pulling”, the force of the exiting strap opens one or more doors, gates or latches that facilitate removing the strap from the chute.
The point along the chute at which the strap exits the chute and re-enters the strapping head is at the re-entry gate assembly. A typical re-entry gate assembly includes opposing doors or gates that are independently urged open to permit the strap to pass from the chute. The gates must have sufficient resistance to stay closed to maintain the strap within the chute, but must also open as the strap exerts sufficient force (e.g., when pulled during re-winding), to the release the strap from the chute.
It has been found that, at times, strap does not release evenly across the face of the gates. In the event that the strap contacts one of the doors prior to, or with greater force than it contacts the other door, the strap can become caught on the gates and at the strapping head, thus causing machine malfunction. It has also been found that, due to the geometry of the cute, and gates, the frame and the load, the strap may not fully strip from the chute during tensioning. As such, again, the strap can become caught on the strapping head causing a machine malfunction.
Accordingly, there exists a need for a re-entry gate assembly for a strapping machine that permits ready re-entry of the strapping material into the strapping head, following traversal through the strap chute. Desirably, such a re-entry gate assembly prevents the strap from becoming caught at the chute and/or strapping head, during tensioning modes (as the strap is pulled from the chute). Most desirably, such a reentry gate assembly urges both gates open with the opening (pivoting) of the strapping head to assure release of the strapping material.